In the manufacture of paper and paperboard, it is often desirable to add to the paper, after wet-web formation and generally during drying of the web, various compositions which impart to the resultant paper various desired properties. Thus, sizing agents, coatings, etc. are added to paper to render it more desirable for specific product applications.
Starch is often applied to paper at the size press, for example, to improve, among other properties, the stiffness of the paper. Stiffness is required where the paper is to be used, for example, in applications, such as container board, packaging papers and fine papers for subsequent ease in machine processing, such as sheet fed printers. In the past, starch and synthetic polymers, such as polyvinylalcohol have not proven- to be universally acceptable for the stiffening of paper because the desired stiffness improvement is not cost effective.
As a result, the search for methods and compositions for imparting stiffness to paper continues, the finding of which continues to satisfy a long felt need.